histo bone and osteogenesis 1

  1. Bone is?
    • HARD
    • -highly specialized CT
    • -has cells and ECM, just like any other CT
  2. Bone has what type of collagen fiber bundles?
    Type 1
  3. GAGS are?/
    hyaluronic acids, chondroitin 4-SO4, keratan SO4
  4. Bone also has?
    • -Ca & PO4 in the form of HYDROXAPATITE CRYSTALS
  5. Collagen fibers and inorganic materials make bone extremely?
  6. Bone is?
    • -relatively light weight
    • -somewhat resilient
  7. Bone is a
    living tissue
  8. What is osteonectin?
    structural proteins that bind things together
  9. What are the structural things that bind things together in cartilage?
  10. What are the structural proteins that bind things together in CT?
  11. Enamel is __% inorganic & ___% organic & water.
    • 96-98%
    • 2-4%
  12. Dentin is ___% inorganic, ___% organic, &  ___% water.
    • -70%
    • -20%
    • -10%
  13. Bone and Cementum are __%inorganic & __% organic+water
    • -65%
    • -35%
  14. The %percentage of inorganic material gets less and less as it gets closer to the pulp.
  15. Because of mineral deposition, bones become ?
    • -calcified
    • -can bear more weight
    • -form rigid skeleton
    • -for muscle attachments
  16. Cartilage is?
    • -semirigid
    • -highly hydrated
    • -higher water content
    • -much more flexible than bone
  17. In x-ray. what tooth is the most white?
    -What tooth tis the most gray?
    • white= enamel
    • gray= pulp (soft)
  18. For an XRAY ID:

    • dentin= gray HARD TISSUE
    • enamel= white on top
    • pulp= most gray SOFT TISSUE
  19. Functions of BONE:
    • -enables SKELETON to maintain the body shape
    • -for PROTECTION, cranium protects the brain, thoracic cage protects the heart, lungs...
    • -serve as LEVERAGE for muscle action, mobility
    • -act as RESERVOIR for ions, especially Ca, released from bone when too low in blood & vice versa
    • -has BONE MARROW for formation of blood cells
  20. Problems occurs because bone is hard:
    • -impossible for diffusion of nutrients/wastes
    • -impossible to grow interstitially from within
    • -impossible to cut section, demineralized first teeth also
    • -miss important parts in DEMINERALIZED OR DECALCIFIED SECTION
  21. Problems occur because bone is hard: ( continued)
    -miss cells/other organic components in DRY GROUND SECTIONS
  22. A long bone:
    • -shaft or DIAPHYSIS, compact bone
    • -ends or epiphyses
  23. Spicules are?
    (small pieces) of SPONGY or CANCELLOUS BONE
  24. Trabeculae are?
    (bigger pieces) of SPONGY or CANCELLOUS BONE
  25. Trabeculae is?
    where cancerous bone is located
  26. Trabeculae and spicules?
    -look different but both have the SAME IDENTICAL cells, fibers, and ground substance
  27. Periosteum?
    covers bone, has 2 layers
  28. Endosteum?
  29. Periosteum and Endosteum?
    -both provide blood supply
  30. What is the Osteon/Haversian system?
    collagen fibers arranged in lamellae/layers concentrically organized around a canal= whole complex
  31. Harversian canal?
    hole in the middle that contains blood vessels & nerves
  32. Where is the OUTER CIRCUMFERENTIAL LAMALLAE located?
    just beneath the periosteum outside
  33. Where is the INNER CIRCUMFERENTIAL LAMELLAE located?
    around the marrow cavity
  34. Intersitial lamellae is?
    irregular lamellae, bits/pieces left after remodeling
  35. Volksmann's canal?
    communicates between osteons together and to the peri/endosteum
  36. Osteoblasts?
    • -lay down Harversian systesms
    • -lay down ECM
    • -trapped in own matrix
    • -become OSTEOCYTES located in lacunae
  37. Where are osteocytes found?
    in lacunae
  38. Short/irrgular bones (mandible/maxillary)?
    spongy bone surrounded by compact bone
    2 plates seperated by dipole
    the first bone formed in embryo and in fracture repair
  41. Primary bone is?
  42. Secondary bone is?
  43. Secondary bone is also called?
    • -mature bone
  44. Dry Bone qualities
    • -osteons, lamellae
    • -Haversian/Volksmann canals
    • -lacunae
    • -canalliculi, calcified matrix

  45. 3 types of bone cells are?
    • 1. osteoblasts
    • 2.osteocytes
    • 3.osteoclasts
  46. Osteoblasts are?
    bone forming cells
  47. Osteoblasts are derived from?
    mesenchymal cells
  48. Where are osteoblasts located?
    located at the surfaces of bone tissue, once cell layer like simple epithelium
  49. Osteoblasts have what type of cytoplasm?
    Basophilic cytoplasm, active protein producing cells
  50. What do osteoblasts lay down?
    lay down organic components (type 1 collagen fiber bundle, GAGS, proteins) of bone matrix first
  51. Osteoblasts add what type of components later?
    inorganic components
  52. What is an OSTEIOD?
    bone like, later of newly formed bone but NOT yet mineralized
  53. Bone can grow by what type of growth?
    by appositional growth ONLY

    -adds on the surface not by interstitial growth
  54. Once surrounded and trapped in their own matrix, osteoblasts stop forming bone, they become?
  55. Osteoblasts have receptors for?
    Parathyroid hormone

    -when activated, will activate and increase the number of osteoclasts
  56. Parathyroid hormone promotes?
    bone RESORPTION, more Calcium in the blood
  57. What happens in MINERALIZATION in both types of bone formation:
    • -decrease in water content
    • -increase in inorganic content
    • -collagen content stays the same, NO CHANGE
  58. Osteocytes are located?
    in lacunae between lamellae
  59. Only __ osteocyte in each space.
  60. Cells contact each other via cytoplasmic processes in ____, molecular exchange/communication via _____.
    • 1. canaliculi
    • 2. gap junctions
  61. In osteocytes, how does the bone get blood supply?
    via canaliculi

    -not by diffusion like cartilage
  62. osteocytes look like?
    -flat, almond shaped cells
  63. Osteocytes activity compared to osteoblasts?
    osteocytes are LESS ACTIVE than osteoblasts, never inactive
  64. Osteoclasts are still actively involved in?
    ECM maintenance
  65. Cells get rid of wastes via?
    gap junctions between them!
  66. Osteoclasts are derived from?
  67. Osteoclasts are?
    cells that break down bone (resorption)
  68. Osteoclasts are?
    • -large
    • -multi nucleated cells with Ruffle border
    • -located at Howship's lacunae
  69. How do osteoclasts attack bone surfacr or resop bone by?
    acid phosphatase enzyme reaction
  70. Osteoclasts have receptors for?

    -secreted by parafollicular of C cells of thyroid gland, which INHIBITS OSTEOCLAST ACTIVITY AND BONE RESORPTION
  71. What is bone remodeling?
    continuously being removed/replaced in both young and old bones
  72. Sharpeys fibers are?
    -Type 1 collagen fiber bundles inserted into the bone
  73. Sharpeys fibers are seen as?
    periodontal ligaments

    -anchoring to the bony tooth socket, or where tendon attached to the bone
  74. Collagen fiber bundles in the matrix give bone its?
    tensile strength
  75. Endosteum is?
    made up of all the cells lining the marrow cavity

    -osteoprogenitor cells, osteoblasts, osteoclasts
  76. A bone spicule is formed by?
    intramembranous formation from head/neck mesenchyme
  77. Intramembranous ossification is?
    direct mineralization of matrix secreted by osteoblasts
  78. Intracatilaginous/endochondral ossification is?
    by deposition of bone matrix on pre-existing cartilage model
  79. In intramembranous ossification and intracartilaginous ossification the first bone tissue is?
    primary bone (immature or woven) then replaced by secondary bone (mature or lamellar)
  80. In intramembranous ossification trapped cells become?
  81. What bones are formed from intramembranous ossification?
    -flat bones of skull and irregular bones, maxilla & mandible (except sphenoccipital join & condyles of mandibles)
  82. In endochondral/intracartiliaginous ossification it occurs within?
    pre-existing catilage model
  83. Endochondral ossification is found in the formation of?
    long/short ones, the condyles of the mandible, sphenocciptial joint
  84. Hyaline cartilage models acts as fetal skeleton, is NOT harden and become bone
  85. Bone collar is produced?
    at local perichondrium
  86. Primary ossification center is?
    at the center
  87. Secondary ossification centers is at?
    both ends
  88. Articular cartilage ?
    persists thru out adult life, does not contribute to bone growth in length
  89. Epiphyseal plate or growth plate is responsible for bone growth in?

    -disappears in adults, strop growing in height, remnants= epiphyseal lines
  90. Step/Zones in endochondral osteogenesis:
    • 1. Resting zone
    • 2. Zone of proliferation
    • 3. Zone of hypertrophy
    • 4. Zone of calcification
    • 5. Zone of ossification
    • 6. Resorption
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histo bone and osteogenesis 1
histo 1